It is sometimes necessary to identify a tick's species, since certain diseases are associated with specific species of ticks. The laboratory testing performed on a removed tick for pathogens may be determined by the species that the tick belongs to. In addition, a clinician may request to know the species if post-exposure prophylaxis is determined clinically necessary.
Stages in development:
(1) larva: smaller than nymph, with six legs
(2) nymph: smaller than adult, with eight legs
(3) adult: full-sized, with eight legs
|
Finding |
Soft Tick (Argasidae) |
Hard Tick (Ixodidae) |
|
dorsal shield (scutum) |
absent |
present |
|
mouth parts (capitulum) |
not visible when tick viewed from dorsum |
visible anteriorly when viewed from dorsum |
Soft Ticks
|
Species |
Suture Line on Side View |
Hypostome (lower lip) |
Integument |
|
Argas |
present |
|
|
|
Ornithodoros |
none |
present between 2 palpi; 50-100% of the palpal length |
warty |
|
Otobius |
none |
vestigial |
granular or spiculated |
|
Antricola |
none |
small and scoop like |
tuberculated |
where:
• The suture line in Argas ticks may be hard to identify if the tick is engorged.
Hard Ticks
General points:
(1) An engorged hard tick may closely resemble a soft tick.
(2) A female tick has a short scutum (vest-like covering) on the dorsum (legs facing away).
(3) Dermacentor and Amblyomma ticks are termed ornate due to whitish markings on the scutum. Other species lack these markings and are termed inornate.
Ixodes (black legged):
(1) anal groove: distinct, and anterior to anus
(2) mouthparts: long
(3) festoons: absent
(4) scutum: inornate
Amblyoma (Lone Star):
(1) palpi: long and thin; much longer than length of basis capituli
(2) festoons: present
(3) scutum: ornate, with eyes; shows a single white marking in females
Aponomma:
(1) palpi: long and thin; much longer than length of basis capituli
(2) scutum: eyes absent, not ornate
Dermacentor (American dog tick, Rocky Mountain tick):
(1) palpi: about as long as the length of the basis capituli
(2) basis capituli: does not extend laterally (beyond lateral margins of palpi)
(3) festoons: 11
(4) scutum: ornate
Anocentor:
(1) anal groove:
(2) palpi: about as long as the length of the basis capituli
(3) basis capituli: does not extend laterally (beyond lateral margins of palpi)
(4) festoons: 7
Rhipicephalus (brown dog tick):
(1) palpi: about as long as the length of the basis capituli, not ridged
(2) basis capituli: extends laterally beyond lateral margins of palpi
(3) festoons: present
Boophilus:
(1) palpi: about as long as the length of the basis capituli, ridged
(2) basis capituli: extends laterally beyond lateral margins of palpi
(3) festoons: absent
Specialty: Infectious Diseases
